Systems, methods and computer program products for mobility management in hybrid satellite/terrestrial wireless communications systems

Abstract

Apparatus, methods and computer program products that support inter-PLMN coordination in registration and handover operations are provided. Hysteresis is introduced in registration of radioterminals in a hybrid terrestrial/satellite mobile communications environment. Inter-PLMN handover techniques are provided, including techniques for coordination of communication of timing information and traffic channel controls.

1 . A method of coordinating communications of a radioterminal with a satellite wireless communications network and a terrestrial wireless communications network, the method comprising: 
 detecting a potential degradation of coverage for the radioterminal while registered with a first one of the satellite wireless communications network and the terrestrial wireless communications network;    determining a duration of the degradation of coverage responsive to detecting the potential degradation of coverage while remaining registered with the first one of the satellite wireless communications network and the terrestrial wireless communications network; and    determining whether to register the radioterminal with a second one of the satellite wireless communications network and the terrestrial wireless communications network responsive to whether the determined duration meets a predetermined criterion.    
     
     
         2 . The method of  claim 1 , wherein determining a duration of the degradation of coverage responsive to detecting the potential degradation of coverage while remaining registered with the first one of the satellite wireless communications network and the terrestrial wireless communications network comprises determining a signal strength for communications between the radioterminal and the first one of the satellite wireless communications network and the terrestrial wireless communications network, and wherein determining whether to register the radioterminal with a second one of the satellite wireless communications network and the terrestrial wireless communications network responsive to whether the determined duration meets a predetermined criterion comprises registering the radioterminal with the second one of the satellite wireless communications network and the terrestrial wireless communications network responsive to the signal strength meeting a predetermined level criterion for a predetermined time interval.  
     
     
         3 . The method of  claim 1:   wherein detecting a potential degradation of coverage for the radioterminal while registered with a first one of the satellite wireless communications network and the terrestrial wireless communications network comprises detecting a potential degradation of coverage for the radioterminal while registered with the terrestrial wireless communications network;    wherein determining a duration of the degradation of coverage responsive to detecting the potential degradation of coverage while remaining registered with the first one of the satellite wireless communications network and the terrestrial wireless communications network comprises determining a duration of the degradation of coverage responsive to detecting the potential degradation of coverage while remaining registered with the terrestrial wireless communications network; and    wherein determining whether to register the radioterminal with a second one of the satellite wireless communications network and the terrestrial wireless communications network responsive to whether the determined duration meets a predetermined criterion comprises registering the radioterminal with the satellite wireless communications network responsive to the signal strength meeting a first predetermined level criterion for a first predetermined time interval; and    wherein the method further comprises:    detecting a potential improvement of coverage by the terrestrial wireless communications network for the radioterminal while registered with the satellite wireless communications network;    determining a duration of the potential improvement of coverage responsive to detecting the potential improvement of coverage while remaining registered with the satellite wireless communications network; and    registering the radioterminal with the terrestrial wireless communications network responsive to the determined duration of the potential improvement of coverage meeting a second predetermined level criterion for a second predetermined time interval.    
     
     
         4 . The method of  claim 3 , wherein the first and second predetermined time intervals are different.  
     
     
         5 . The method of  claim 4 , wherein the second predetermined time interval is less than the first predetermined time interval.  
     
     
         6 . The method of  claim 1 , further comprising foregoing registration of the radioterminal with the second one of the satellite wireless communications network and the terrestrial wireless communications network responsive to the radioterminal transiting through a coverage hole of the first one of the satellite wireless communications network and the terrestrial wireless communications network before expiration of a predetermined time interval.  
     
     
         7 . An apparatus for coordinating communications of a radioterminal with a satellite wireless communications network and a terrestrial wireless communications network, the apparatus comprising: 
 a handover controller configured to detect a potential degradation of coverage for the radioterminal while registered with a first one of the satellite wireless communications network and the terrestrial wireless communications network, to determine a duration of the degradation of coverage responsive to detecting the potential degradation of coverage while remaining registered with the first one of the satellite wireless communications network and the terrestrial wireless communications network and to determine whether to register the radioterminal with a second one of the satellite wireless communications network and the terrestrial wireless communications network responsive to whether the determined duration meets a predetermined criterion.    
     
     
         8 . The apparatus of  claim 7 , wherein the handover controller is configured to determine a signal strength for communications between the radioterminal and the first one of the satellite wireless communications network and the terrestrial wireless communications network and to register the radioterminal with the second one of the satellite wireless communications network and the terrestrial wireless communications network responsive to the signal strength meeting a predetermined level criterion for a predetermined time interval.  
     
     
         9 . The apparatus of  claim 7 , wherein the handover controller is configured to detect a potential degradation of coverage for the radioterminal while registered with the terrestrial wireless communications network, to determine a duration of the degradation of coverage responsive to detecting the potential degradation of coverage while remaining registered with the terrestrial wireless communications network and to register the radioterminal with the satellite wireless communications network responsive to the signal strength meeting a first predetermined level criterion for a first predetermined time interval, and 
 wherein the handover controller is further configured to detect a potential improvement of coverage by the terrestrial wireless communications network for the radioterminal while registered with the satellite wireless communications network, to determine a duration of the potential improvement of coverage responsive to detecting the potential improvement of coverage while remaining registered with the satellite wireless communications network and to register the radioterminal with the terrestrial wireless communications network responsive to the determined duration of the potential improvement of coverage meeting a second predetermined level criterion for a second predetermined time interval.    
     
     
         10 . The apparatus of  claim 9 , wherein the first and second predetermined time intervals are different.  
     
     
         11 . The apparatus of  claim 10 , wherein the second predetermined time interval is less than the first predetermined time interval.  
     
     
         12 . The apparatus of  claim 7 , wherein the handover controller is further configured to forego registration of the radioterminal with the second one of the satellite wireless communications network and the terrestrial wireless communications network responsive to the radioterminal transiting through a coverage hole of the first one of the satellite wireless communications network and the terrestrial wireless communications network before expiration of a predetermined time interval.  
     
     
         13 . A system comprising: 
 a satellite wireless communications network;    a terrestrial wireless communications network; and    a handover controller configured to detect a potential degradation of coverage for the radioterminal while registered with a first one of the satellite wireless communications network and the terrestrial wireless communications network, to determine a duration of the degradation of coverage responsive to detecting the potential degradation of coverage while remaining registered with the first one of the satellite wireless communications network and the terrestrial wireless communications network and to determine whether to register the radioterminal with a second one of the satellite wireless communications network and the terrestrial wireless communications network responsive to whether the determined duration meets a predetermined criterion.    
     
     
         14 . The system of  claim 13 , wherein the handover controller is configured to determine a signal strength for communications between the radioterminal and the first one of the satellite wireless communications network and the terrestrial wireless communications network and to register the radioterminal with the second one of the satellite wireless communications network and the terrestrial wireless communications network responsive to the signal strength meeting a predetermined level criterion for a predetermined time interval.  
     
     
         15 . The system of  claim 13 , wherein the handover controller is configured to detect a potential degradation of coverage for the radioterminal while registered with the terrestrial wireless communications network, to determine a duration of the degradation of coverage responsive to detecting the potential degradation of coverage while remaining registered with the terrestrial wireless communications network and to register the radioterminal with the satellite wireless communications network responsive to the signal strength meeting a first predetermined level criterion for a first predetermined time interval, and 
 wherein the handover controller is further configured to detect a potential improvement of coverage by the terrestrial wireless communications network for the radioterminal while registered with the satellite wireless communications network, to determine a duration of the potential improvement of coverage responsive to detecting the potential improvement of coverage while remaining registered with the satellite wireless communications network and to register the radioterminal with the terrestrial wireless communications network responsive to the determined duration of the potential improvement of coverage meeting a second predetermined level criterion for a second predetermined time interval.    
     
     
         16 . The system of  claim 15 , wherein the first and second predetermined time intervals are different.  
     
     
         17 . The system of  claim 16 , wherein the second predetermined time interval is less than the first predetermined time interval.  
     
     
         18 . A computer program product for coordinating communications of a radioterminal with a satellite wireless communications network and a terrestrial wireless communications network, the computer program product comprising computer program code embodied in a computer readable medium, the computer program code comprising: 
 program code configured to detect a potential degradation of coverage for the radioterminal while registered with a first one of the satellite wireless communications network and the terrestrial wireless communications network, to determine a duration of the degradation of coverage responsive to detecting the potential degradation of coverage while remaining registered with the first one of the satellite wireless communications network and the terrestrial wireless communications network and to determine whether to register the radioterminal with a second one of the satellite wireless communications network and the terrestrial wireless communications network responsive to whether the determined duration meets a predetermined criterion.    
     
     
         19 . The computer program product of  claim 18 , wherein the computer program code comprises program code configured to determine a signal strength for communications between the radioterminal and the first one of the satellite wireless communications network and the terrestrial wireless communications network and to register the radioterminal with the second one of the satellite wireless communications network and the terrestrial wireless communications network responsive to the signal strength meeting a predetermined level criterion for a predetermined time interval.  
     
     
         20 . The computer program product of  claim 18 , wherein the computer program code comprises program code configured to detect a potential degradation of coverage for the radioterminal while registered with the terrestrial wireless communications network, to determine a duration of the degradation of coverage responsive to detecting the potential degradation of coverage while remaining registered with the terrestrial wireless communications network and to register the radioterminal with the satellite wireless communications network responsive to the signal strength meeting a first predetermined level criterion for a first predetermined time interval; and 
 wherein the computer program code further comprises program code configured to detect a potential improvement of coverage by the terrestrial wireless communications network for the radioterminal while registered with the satellite wireless communications network, to determine a duration of the potential improvement of coverage responsive to detecting the potential improvement of coverage while remaining registered with the satellite wireless communications network and to register the radioterminal with the terrestrial wireless communications network responsive to the determined duration of the potential improvement of coverage meeting a second predetermined level criterion for a second predetermined time interval.    
     
     
         21 . The computer program product of  claim 20 , wherein the first and second predetermined time intervals are different  
     
     
         22 . The computer program product of  claim 21 , wherein the second predetermined time interval is less than the first predetermined time interval.  
     
     
         23 . The computer program product of  claim 18 , wherein the computer program code further comprises program code configured to forego registration of the radioterminal with the second one of the satellite wireless communications network and the terrestrial wireless communications network responsive to the radioterminal transiting through a coverage hole of the first one of the satellite wireless communications network and the terrestrial wireless communications network before expiration of a predetermined time interval.  
     
     
         24 . A method of operating first and second public land mobile networks (PLMNs), the method comprising: 
 conducting a call between a radioterminal and the first PLMN;    during the call, detecting transit of the radioterminal into a coverage area of the second PLMN; and    handing over the radioterminal to the second PLMN while maintaining the call.    
     
     
         25 . The method of  claim 24 , further comprising conducting a location update of the radioterminal in the second PLMN responsive to termination of the call.  
     
     
         26 . The method of  claim 24 , wherein initiation of the call is preceded by exchanging subscriber-registration-related information between the first and second PLMNs, and wherein handing over comprises handing over using the exchanged subscriber-registration-related information.  
     
     
         27 . The method of  claim 26 , wherein handing over comprises handing over without an authentication communication between the radioterminal and the second PLMN based on a trust relationship between the first and second PLMNs.  
     
     
         28 . The method of  claim 27 , further comprising the first PLMN denying handover of a second radioterminal to the second PLMN based on the trust relationship.  
     
     
         29 . The method of  claim 24 , wherein handing over is preceded by providing PLMN-identifying information for candidate handover frequencies in the second PLMN to the radioterminal.  
     
     
         30 . The method of  claim 24 , further comprising generating respective records of charges in the first and second PLMNs for the call.  
     
     
         31 . The method of  claim 30 , wherein the first PLMN comprises a terrestrial PLMN and wherein the second PLMN comprises a satellite PLMN and wherein generating respective records of charges in the first and second PLMNs for the call comprises: 
 initiating a charge record for the call in the first PLMN responsive to initiation of the call in the first PLMN;    responsive to detecting handover of the radioterminal to the second PLMN, identifying the radioterminal as a subscriber to the second PLMN; and    initiating a charge record for the call in the second PLMN responsive to identifying the radioterminal as a subscriber to the second PLMN.    
     
     
         32 . The method of  claim 31 , wherein identifying the radioterminal as a subscriber to the second PLMN comprises querying the radioterminal for a subscriber identifier.  
     
     
         33 . An apparatus for supporting interoperation of first and second public land mobile networks (PLMNs), the apparatus comprising: 
 a inter-PLMN handover controller configured to support a call between a radioterminal and the first PLMN, to detecting transit of the radioterminal into a coverage area of the second PLMN during the call, and to hand over the radioterminal to the second PLMN while maintaining the call.    
     
     
         34 . The apparatus of  claim 33 , wherein the inter-PLMN handover controller is further configured to conduct a location update of the radioterminal in the second PLMN responsive to termination of the call.  
     
     
         35 . A system comprising: 
 first and second public land mobile networks (PLMNs); and    a inter-PLMN handover controller configured to support a call between a radioterminal and the first PLMN, to detect transit of the radioterminal into a coverage area of the second PLMN during the call, and to hand over the radioterminal to the second PLMN while maintaining the call.    
     
     
         36 . The system of  claim 35 , wherein the inter-PLMN handover controller is further configured to conduct a location update of the radioterminal in the second PLMN responsive to termination of the call.  
     
     
         37 . The system of  claim 35 , wherein the inter-PLMN handover controller is configured to hand over the call without an authentication communication between the radioterminal and the second PLMN based on a trust relationship between the first and second PLMNs.  
     
     
         38 . The system of  claim 37 , wherein the first PLMN is configured to deny handover of a second radioterminal to the second PLMN based on the trust relationship.  
     
     
         39 . The system of  claim 35 , wherein the first PLMN is configured to provide PLMN-identifying information for candidate handover frequencies in the second PLMN to the radioterminal.  
     
     
         40 . The system of  claim 35 , further comprising means for generating respective records of charges in the first and second PLMNs for the call.  
     
     
         41 . A computer program product for coordinating operations of first and second public land mobile networks (PLMNs), the computer program product comprising computer program code embodied in a computer readable medium, the computer program code comprising: 
 program code configured to support a call between a radioterminal and the first PLMN, to detect transit of the radioterminal into a coverage area of the second PLMN during the call, and to hand over the radioterminal to the second PLMN while maintaining the call.    
     
     
         42 . The computer program product of  claim 41 , wherein the computer program code further comprises program code configured to conduct a location update of the radioterminal in the second PLMN responsive to termination of the call.  
     
     
         43 . The computer program product of  claim 41 , wherein the computer program code comprises program code configured to hand over the radioterminal without an authentication communication between the radioterminal and the second PLMN based on a trust relationship between the first and second PLMNs.  
     
     
         44 . The computer program product of  claim 43 , wherein the computer program code further comprises program code configured to generate respective records of charges in the first and second PLMNs for the call.  
     
     
         45 . A method of conducting wireless communications, the method comprising: 
 conducting a communications session between a radioterminal and a terrestrial wireless communications system;    detecting a condition for handover of the session from the terrestrial wireless communications system to a satellite wireless communications system;    responsive to detection of the condition for handover, communicating timing information for communications with the satellite wireless communications system from the terrestrial wireless communication system to the radioterminal; and    responsive to the communication of the timing information, conducting a communications session between the radioterminal and the satellite wireless communications system using the communicated timing information.    
     
     
         46 . The method of  claim 45 , wherein the timing information comprises information for alignment with a timing epoch  
     
     
         47 . The method of  claim 45 , wherein the timing information comprises a timing advance.  
     
     
         48 . The method of  claim 45 , further comprising determining the timing information from information about relative positioning of components the terrestrial wireless communications system and the satellite wireless communications system.  
     
     
         49 . The method of  claim 47 , wherein the components comprise a base station antenna and a satellite.  
     
     
         50 . The method of  claim 47 , wherein the components comprise the radioterminal and a satellite.  
     
     
         51 . An apparatus, comprising: 
 a handover controller configured to support a communications session between a radioterminal and a terrestrial wireless communications system, to detect a condition for handover of the session from the terrestrial wireless communications system to a satellite wireless communications system, to communicate timing information for communications with the satellite wireless communications system from the terrestrial wireless communication system to the radioterminal responsive to detection of the condition for handover, and to conduct a communications session between the radioterminal and the satellite wireless communications system using the communicated timing information responsive to the communication of the timing information.    
     
     
         52 . The apparatus of  claim 51 , wherein the timing information comprises information for alignment with a timing epoch.  
     
     
         53 . The apparatus of  claim 51 , wherein the timing information comprises a timing advance.  
     
     
         54 . The apparatus of  claim 51 , wherein the controller is further configured to determine the timing information from information about relative positioning of components the terrestrial wireless communications system and the satellite wireless communications system.  
     
     
         55 . The apparatus of  claim 54 , wherein the components comprise a base station antenna and a satellite.  
     
     
         56 . The apparatus of  claim 54 , wherein the components comprise the radioterminal and a satellite.  
     
     
         57 . A computer program product for supporting wireless communications, the computer program product comprising computer program code embodied in a computer readable medium, the computer program code comprising: 
 program code configured to support a communications session between a radioterminal and a terrestrial wireless communications system, to detect a condition for handover of the session from the terrestrial wireless communications system to a satellite wireless communications system, to communicate timing information for communications with the satellite wireless communications system from the terrestrial wireless communication system to the radioterminal responsive to detection of the condition for handover and to conduct a communications session between the radioterminal and the satellite wireless communications system using the communicated timing information responsive to the communication of the timing information.    
     
     
         58 . The computer program product of  claim 57 , wherein the timing information comprises information for alignment with a timing epoch  
     
     
         59 . The computer program product of  claim 57 , wherein the timing information comprises a timing advance.  
     
     
         60 . The computer program product of  claim 45 , wherein the computer program code further comprises program code configured to determine the timing information from information about relative positioning of components the terrestrial wireless communications system and the satellite wireless communications system.  
     
     
         61 . The computer program product of  claim 60 , wherein the components comprise a base station antenna and a satellite.  
     
     
         62 . The computer program product of  claim 60 , wherein the components comprise the radioterminal and a satellite.  
     
     
         63 . A method of handing over communications of a radioterminal from a terrestrial wireless communications system to a satellite wireless communications system, the method comprising: 
 communicating a handover command message from the terrestrial wireless communications system to the radioterminal; and    responsive to receipt of the handover command message at the radioterminal, waiting a time interval before terminating a traffic channel between the radioterminal and the terrestrial wireless communications system    
     
     
         64 . The method of  claim 63 , wherein the time interval is sufficient to determine and communicate timing information for the satellite wireless communications system to the radioterminal.  
     
     
         65 . The method of  claim 64 , wherein the timing information comprises a timing advance.  
     
     
         66 . The method of  claim 63 , further comprising determining the time interval responsive to receipt of a physical information message from the satellite wireless communications system at the radioterminal.  
     
     
         67 . The method of  claim 63 , wherein terminating a traffic channel comprises communicating a handover command acknowledgment from the radioterminal to the terrestrial wireless communications system.  
     
     
         68 . A radioterminal comprising; 
 a handover controller configured to receive a handover command message from a terrestrial wireless communications system for handover to a satellite wireless communications system and to wait a time interval before terminating a traffic channel between the radioterminal and the terrestrial wireless communications system responsive to receipt of the handover command message at the radioterminal.    
     
     
         69 . The radioterminal of  claim 68 , wherein the time interval is sufficient to determine and communicate timing information for the satellite wireless communications system to the radioterminal.  
     
     
         70 . The radioterminal of  claim 69 , wherein the timing information comprises a timing advance.  
     
     
         71 . A computer program product for controlling handover of a radioterminal from a terrestrial wireless communications system to a satellite wireless communications system, the computer program product comprising computer program code embodied in a computer readable medium, the computer program code comprising: 
 program code configured to receive a handover command message from the terrestrial wireless communications system and to cause the radioterminal to wait a time interval before terminating a traffic channel between the radioterminal and the terrestrial wireless communications system responsive to receipt of the handover command message at the radioterminal.    
     
     
         72 . The computer program product of  claim 71 , wherein the time interval is sufficient to determine and communicate timing information for the satellite wireless communications system to the radioterminal.  
     
     
         73 . The computer program product of  claim 72 , wherein the timing information comprises a timing advance.